Tatsuo Senō, known as Chief, leads the village firefighting force on Shikotan Island, making him a de facto community leader responsible for local safety and coordination. A single father, he raises his sons Junpei and Kanta with support from their grandfather Genzō after their mother's death. His leadership extends beyond firefighting during wartime, encompassing oversight of the island's civilian defense while trained soldiers handle military installations.

When Soviet forces occupy Shikotan following Japan's WWII surrender, Tatsuo organizes a covert food distribution network using hidden military stockpiles to prevent starvation among displaced Japanese residents, collaborating with the village schoolteacher, Sawako. His resistance intensifies when his opportunistic brother Hideo tries to divert supplies for black market sales, ultimately leading to Tatsuo's discovery and arrest by Soviet authorities.

Captured, Tatsuo is imprisoned separately from his family during their forced relocation to internment camps. His sons undertake a perilous journey to reach his camp, resulting in a fleeting but charged reunion across barbed wire where Tatsuo makes an impossible promise of reunion. Later scenes confirm his eventual death in captivity when Junpei visits his grave decades after the war during a return to Shikotan. His arc epitomizes the fractures of families during postwar displacements; his fate hangs unresolved beyond imprisonment until the epilogue.